With the establishment of NATO in April of 1949, there arose a need for standardization among its members regarding various military tools. Among them were aircraft types which would come into play for a war against the Soviet Union over Europe. As such, authorities in 1953 called for a standardized lightweight fighter-bomber to stock inventories of member countries and keep Soviet bombers at bay. One result of this initiative - which was won by the Italian Fiat G.91 of 1958 - was the ultimately-cancelled French-made SNCASE (Sud-Est) SE.212 "Durandal", which ended as an intended dedicated fighter-interceptor.
One of the key qualities of the Durandal was a mixed-powerplant approach primarily relying on a turbojet engine backed by a rocket motor to achieve desired speeds. The overall design - evolved from work begun as early as 1951 by the French - was given a small-area, low-mounted wing mainplane featuring 60-degree sweep lines. The mainplanes were of a delta configuration which negated use of conventional horizontal tailplanes. The tail unit consisted of a triangular vertical fin with the engine exhaust ring fitted underneath. The cockpit was held well-forward of midships and the nose section given a slight nose-down attitude. The engine, buried within the fuselage mass, was aspirated by a circular intake at the nose. Propulsion was provided for by the SNECMA Atar 101F afterburning engine offering 8,377 lb of thrust. The rocket unit was a SEPR 75 motor providing its own 1,653 lb of thrust. The undercarriage was a conventional tricycle arrangement, fully-retractable. Airbrakes were fitted in pairs along the sides of the rear section of the fuselage, springing to action when called upon.
As an interceptor, it was seen that the SE.212 was to be armed with a sole R.052 or AA.20 air-to-air missile (along fuselage centerline). Alternatively the airframe could be outfitted with more conventional cannons (2 x 30mm DEFA systems) and even carry 24 x 68mm SNEB air-to-air rockets for bomber interception.
French authorities were interested in the SE.212 design enough to order a pair of prototypes, the first of these to fly on April 20th, 1956- though without its intended rocket unit. It was not until December 19th, of that year that the aircraft flew with its rocket motor functioning and, by this time, the original Atar 101F turbojet engine was succeeded by the Atar 101G series providing 9,700 lb of thrust. The second prototype went aloft on March 30th, 1957 and this example went on to be displayed at the 1957 Paris Air Show.
During testing that began in April of 1956, the pair recorded speeds reaching nearly 900 miles per hour - over Mach 1.0 - and, with the rocket motor activated, reached 1,036 miles per hour, or about Mach 1.57 at 38,000-39,000 feet.
Despite these results, the Durandal initiative faded into history as the program was ended during 1958 with just the two experimental vehicles being completed. Many "mixed-powerplant" fighter developments of the period ended their days as prototypes and nothing more - the concept was also of considerable interest to the Americans.